Marc Gasol
Brook Lopez
Big Baby plays tons of center
Greg Monroe can easily and does do the #1 gogo at times

That's 25% of the NBA and where does Tim Duncan sit as far as option #?

edit: and in fact if you add David Lee it's even higher and that's all the centers there are, that's all there ever are really, and as I've pointed out before this generation of 7 footers has been destroyed by injury so you've got a normal looking NBA in spite of the insipid "jordanaire" typecasting of the league.
Now if they just return to real rules regarding hand-checking defense we'll have it all!!